A suspension of a vehicle responds to various road impacts encountered while the vehicle is being driven, and controls dynamics of the vehicle under acceleration/deceleration and turns. One important role of such a suspension is to reduce transmission of noise and vibration into a vehicle body.
In a typical suspension of a vehicle, a spring and a damper (also called a shock absorber) is mounted to each wheel. A spring coefficient (also called a spring rate or a spring constant) of the spring, a damping coefficient of the damper, and mounting positions of the springs and dampers are determined in the designing process of the suspension. Therefore, a great deal of research has been undertaken to enhance performance of a suspension by efficiently determining such design factors.
However, the amount of possible enhancement of the performance of a suspension by simply changing such design factors is limited. So recently, new research has been undertaken to actively eliminate vibration of the suspension by utilizing a plurality of excitation actuators mounted to a suspension system. Such excitation actuators may be disposed with each spring/damper for each wheel.
For example, through a process called direct velocity feedback control, vibration energy may be dissipated by increasing the damping effect in a vehicle suspension system that has multiple degrees of freedom. Such a technique shows a merit in that asymptotic stability is ensured.
However, in order to obtain asymptotic stability by such direct velocity feedback control, many sensors and excitation actuators are required. This is problematic because equations of motion of a suspension become inter-coupled when modeling the vehicle suspension by equations of motion.
Therefore, recently, research has been undertaken to design a suspension such that the equations of motion thereof become non-coupled, or to determine what actuating forces should be applied to such a designed suspension.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.